Radiation emitted by cellular telephones has been recognized as a potential worldwide health hazard. Although it is commonly believed that the power output of the cellular telephone is constant over time, this is not borne out by facts.
CDMA cellular telephones vary their power over a very wide range. TDMA and GSM cellular telephones usually switch between “high” and “low” power in inverse relation to their proximity to the cell. The cellular telephones determine how to vary their power levels by measuring the reception level of the cellular telephone from the nearest cell. Therefore, the radiation emitted by cellular telephones while in transmission mode is not constant over time. These facts, taken with the potential and serious health hazards, provide great medical and economic motivation to measure and compute the actual radiation power and exposure, and to compare the results with known health-protection standards.
The International Commission on Non Ionizing Radiation Protection (ICNIRP) and its American counterpart ANSI/IEEE are organizations that have defined recognized standards for radiation limits that are indisputable in the cellular industry, scientific, and health communities. Lacking evidence of carcinogenic side effects from exposure to cellular telephones from other bodies, the standards defined by the above organizations may provide safety criteria. These standards are recognized and accepted by the cellular telephones and wireless communication equipment manufacturers.
ICNIRP, in its October 1997 guidelines document, “Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic, and Electromagnetic Fields (up to 300 Hz)” (published in health physics, April 1998, volume 74, number 4), states the exposure limitation values for the general public.
For example, the permitted exposure levels are defined in power density units (e.g. W/m2) or in specific energy absorption rate (SAR) units (e.g. Watt/Kg). The permitted Level for the public, in the 900 MHz frequency range, is 2 Watt/Kg in the head and trunk parts of the body. Calculations and mathematical modeling give a reference-electromagnetic field (EMF) value of 41 V/m or power density of 0.45 mW/square cm.
Any person skilled in this field understands that although the ICNIRP standard is the respected norm today, it might be updated or replaced by a different and even more cautious standard in the coming years, as knowledge regarding electromagnetic radiation health hazardous expands.
While companies in the cellular telephone arena are aware and apprehensive of dangers emanating from emitted radiation and the standard (e.g., ICNIRP) is known and accepted, the technology for providing cellular telephones with warning capability lags far behind. Laboratory equipment and test instruments that measure levels of electromagnetic radiation are known. However, these instruments are expensive (cost hundreds and thousands of dollars), bulky and impractical for daily use for the public. The field of electromagnetic measurements by probes and related equipment is considered highly specialized and out of the scope of the general public.
Some low cost accessories in the market provide a flashing light emitting diode (LED), a buzzer, or vibration warning when detecting a strong radio frequency (RF) signal in their vicinity. Although these components draw the cellular telephone user's attention to an incoming call, they do not provide any early warning regarding emitted radiation, as they all operate momentarily, regardless of the accumulated energy absorbed by the user. All these existing technologies therefore have no relevance to safety issues.
Some analog and digital units available on the market detect and measure radiation leakage, For example, instruments that measure radiation leakage from microwave ovens. These units are momentary power meters which do not take into account the long term accumulated exposure. It is up to the user to decide whether the electromagnetic lee level is acceptable.
Additionally, several ‘passive’ protection accessories have been introduced recently on the market. For example, electromagnetic shields in the form of cellular telephone cases. These cases include a cover for the antenna, and are made of materials that ‘absorb’ electromagnetic radiation.
These cases are heavy and must be produced in different sizes and shapes, because of constant changes in cellular telephones sizes and shapes. Since the cases hide the antenna, they have an adverse affect on the quality of reception and/or transmission of the cellular telephone. The protective cases provide a constant protection level regardless of the changing levels of electromagnetic radiation that the cellular telephones emit in the course of operation.